A known rubber pad press comprises an upper frame member or head, a lower frame member or bed and a working piston-and-cylinder device. The lower frame member and upper frame member are coupled in a press frame by an anchor bolt. The lower frame member carries a platen and a tool mounted on the platen. A receiving chamber formed in a device which supports the chamber and the interior pressing force exerted thereon is located in the upper frame member. The rubber pad is positioned in this receiving chamber.
In a rubber press pad as taught in German Pat. No. 30 04 616 the lower frame member or bed contains the cylinder of the working piston-and-cylinder unit. The piston guided in it carries the platen with the tool. The receiving chamber or casing for the rubber pad is in the upper frame member or head as noted. The device for maintaining the chamber interior pressure during operation of the rubber pad press comprises a binding or rim which surrounds the lower frame member in the vicinity of the receiving chamber. The binding rim forms an additional mechanical structural member which must be assembled with the press and is expensive to manufacture. Also it must be designed to take the highest working pressure of the rubber pad press and it thus must usually be overdimensioned to prevent distortion of the casing. On the other hand a special unit for maintaining the chamber interior pressure is required to guarantee that the casing and the upper frame member will not be damaged by an overload.